Mandibular advancement splint

ABSTRACT

Mandibular advancement splint against snoring and sleep apnea. The splint is made of two thermoformable trays ( 1, 2 ) designed to envelop the upper and lower arch. In order to be able to adapt to individual variations in conformation, the advancement splint includes an articulated frame having rigid and flexible elements, immersed in the thermoformable flexible material or molded around it. The frame&#39;s articulations ( 12, 13, 23 ) allow the splint to fit the curve of the dental arch and to adapt to irregularities in the teeth&#39;s position. The inventive splint is equivalent in terms of comfort and efficiency to a personalized splint made by an orthodontist or dental technician, but its cost is 6 to 10 times lower.

REFERENCE DATA

This application is a continuation of international patent applicationPCT/EP2005/052431, filed on May 27, 2005, claiming priority formEuropean patent application EP04102543, filed on Jun. 4, 2004, bothincorporated herewith by reference.

TECHNICAL FIELD

The present invention relates to the field of mouth correctiveappliances and notably to a mandibular advancement splint for treatingsnoring and night apnea.

RELATED ART

Snoring is a well-known acoustic expression whose anatomic andphysiological causes are connected to a muscular hypotonia that appearsduring sleep. The mandible, normally held by the action of the muscles,in fact tends to move backwards during sleep, its movement causing thetongue to move towards the back of the mouth and thus the size of theupper air tract to diminish. The resulting turbulences of therespiratory flow, amplified by vibration and resonance phenomena of thesoft palate (velum palatinum) and of the adjacent soft parts, are theorigin of the snoring sound that can, in certain cases, reach anextremely high intensity.

Snoring is not limited to disturbing, even severely, the quality ofsleep of the household and relatives of the afflicted person. Sometimes,especially with individuals suffering from macroglossia or from asmall-size mouth cavity, or if the laxity of the tissues is high, theobstruction of the breathing canal can be serious or even complete,causing in fact the breathing to be interrupted or obstructive sleepapnea.

In this case, snoring is one aspect of a true pathology that also showsthrough the fragmentation of sleep provoking drowsiness during the dayand lessened concentration abilities. Apnea causes hypoxia, bradycardiafollowed by tachycardia with risks of hypertension. This apnea is likelyto trigger a nocturnal cardio-respiratory arrest.

It is known how to treat efficiently snoring and night apnea by wearingduring the night a nasal mask blowing air under pressure into thepharynx. This solution however places an excessive constraint upon thewearer and requires individual calibrations for each patient, as well aspolysomnographic efficiency controls. For these reasons, the applicationof this type of treatment is restricted to obstructive syndromes and isnot justified for treating simple snoring. Prolonged use is likely forthe treatment to cause nasal symptoms of the rhinitis type or skin soresthat make it impossible to wear the mask.

It is also known how to treat snoring and sleep apnea by surgicalresection of the soft palate, possibly completed with surgical maxillaryadvancement. This solution is however invasive and painful, and theresulting improvement is only transitory. Furthermore, it can involvechanges of the mouth morphology that can disturb deglutition. Thishighly invasive operation is nowadays practically abandoned.

To fight snoring, mouth appliances that hook onto the upper and lowerdental arches have been proposed, allowing the mandible to be advancedforward even in the absence of sufficient muscular tension. Patentapplication DE198628 describes an example of such a mono-bloc device ofthe type immobilizing completely the mandible in advanced position.Having the mandible immobilized can prove discomforting for the wearer,notably in that it interferes with deglutition and can cause analgo-dysfunctional syndrome (ADS) of the temporo-mandibular joint (TMJ).

Patent EP0845962B describes a thermoformable articulated devicecombining supple and semi-rigid elements and allowing a certain freedomof movement of the mandible whilst advancing it forward. This deviceconsists of two trays made of thermoformable material. In this manner,each patient can adapt the trays to his own conformation by heating in awater bath at a temperature sufficient for softening the thermoformablelayer and then by molding them on the corresponding arch.

The conformation of the teeth and of the dental arches varies howeverconsiderably from one individual to another, either because the archescan be more or less wide for each individual, or because the teeth arenot regularly positioned along each arch. The adaptability of knownthermoformable devices is very limited and they cannot adapt to the fullrange of possible conformations.

When the mouth appliance cannot adapt perfectly to the individual dentalconformation, the efficiency is reduced, the device is instable, thereare excessive tensions on the dentition and the adaptation of the systemis very uncomfortable. Furthermore, following the involuntary movementsof clamping the mandible, high and concentrated mechanical efforts canoccur on the trays' semi-rigid elements that can cause the device torupture.

Another limitation of this type of appliances is that if it does notadapt perfectly to the dental conformation, it can, during use, exertlateral forces on the teeth that can be of high intensity. These lateralforces can, in time, lead to a displacement and destabilization of theteeth and to their definitive loss.

It is also known to make mandibular advancement splints speciallymanufactured to adapt to the wearer's dental conformation. In this case,each splint is made as a unique part according to the impression of thewearer's jaw bone and mandible, by conventional methods in the field oforthodontics. It will be easily conceived that the manufacturing cost ofthis kind of personalized apparatus is considerably higher than that ofan adaptable splint manufactured in series.

Another limitation of the known mandibular devices, such as for examplethe devices described by EP0845962B, that allow a certain freedom ofmovement of the mandible, is that the latter can, following involuntarymovements during sleep, abandon the forward advanced position. Thedevice then completely loses its efficiency. In these cases, the freedomof movement in the backward direction paradoxically goes against thesought aim of mandibular advancement.

U.S. Pat. No. 5,829,441 describes a mandibular advancement splint havingtwo flexible frames, allowing a deformation and an adaptation of thesplint to different dental conformations, during a molding phase.

The wearer's position during sleep can also influence negatively thegood functioning of the known mandibular devices. It is for examplefrequent for the mandible to abandon the forward advanced position whenthe head is positioned on the side.

It is also known that certain phases of sleep are characterized by avery high activity and muscular tonicity. Once these phases of agitatedsleep over, the prior art devices are not always capable ofautomatically bringing the mandible in the advanced therapeuticposition.

Another limitation of the known devices capable of being personalized isthat they are based on a conventional mouth geometry where the teeth areparallel and arranged on two plane arches. These splints are not capableof adapting to most real dental conformations.

BRIEF SUMMARY OF THE INVENTION

One aim of the present invention is to propose a mandibular advancementsplint that is without the disadvantages of the prior art.

Another aim of the present invention is to propose a mouth deviceagainst snoring that can adapt to a very large number of individualconformations without irreversible risks for the user's dentition.

Another aim of the present invention is to propose a mouth deviceagainst snoring that is more comfortable than the known devices.

Yet another aim of the present invention is to propose a mandibularadvancement splint that can adapt to the wearer's dental conformationhaving the comfort and efficiency equal to those of a personalizedsplint and a reduced production cost.

These aims are achieved by the device that is the object of the mainclaim.

BRIEF DESCRIPTION OF THE FIGURES

The invention will be better understood in the light of the followingdescription, claims and figures in which notably:

FIGS. 1 and 2 represent diagrammatically a mandibular advancement splintof known type;

FIG. 3 represents diagrammatically a device having convex slidingstriations and allowing an air flow to pass according to one aspect ofthe invention;

FIG. 4 represents diagrammatically a device having a flexible outerframe according to one aspect of the present invention;

FIG. 5 represents diagrammatically a later variant embodiment of adevice having a flexible outer frame according to one aspect of thepresent invention;

FIG. 6 represents diagrammatically a device having a flexible innerframe according to one aspect of the present invention;

FIGS. 7 and 8 represent diagrammatically two sections of the device ofFIG. 5;

FIG. 9 represents diagrammatically one section of the device of FIG. 5inserted into a cradle for taking impressions;

FIG. 10 represents diagrammatically a calibrated temperature indicatorused in the method for taking impressions according to the invention;

FIGS. 11 and 12 represent diagrammatically another embodiment of theinvention comprising a surface inclined relative to the main slidingplane;

FIGS. 13, 14 and 15 represent diagrammatically another embodiment of theinvention;

FIGS. 16 and 17 show diagrammatically another embodiment of theinvention comprising an elastic tongue;

FIG. 18 represents diagrammatically a cross section of the extrados ofan splint according to the invention along the plane AA of FIG. 12;

FIG. 19 represents diagrammatically a top view of the lower element ofthe inventive splint according to a preferred variant of the embodimentof FIG. 6;

FIGS. 20, 21, 22 and 23 represent diagrammatically and in threedimensions the upper and lower elements of a device according to theinvention as well as the respective flexible outer frames.

EXAMPLES OF EMBODIMENTS OF THE INVENTION

FIG. 1 represents an intra-buccal device against snoring of known type.It is composed of two trays 1, 2 designed to wrap the upper resp. lowerdental arch. With reference to FIG. 2, the trays 1 and 2 have anextrados essentially rigid 3 on which a thermoformable intrados 4 ismolded. The trays are connected to one another by the hooks 5 and 7 andthe elastic loops 6, in order to exert on the mandible an advancementforce whilst allowing a certain freedom of movement. The rigid extradosof this device is incapable of following an irregular dentition.

During use, the plane surfaces 8 of the two extrados find themselves incontact along the occlusion plane. The mandible's laterality and forwardand backward movements thus include a sliding of these surfaces 8 oneagainst the other.

In order to allow a personalized adaptation of this apparatus, eachpatient can adapt the trays to his own conformation by molding thethermoformable intrados on the corresponding arch, after having softenedit bys immersing it in a water bath at an appropriate temperature.

The device of FIG. 1 thus has a good conformability as long as all theteeth are positioned correspondingly to the flexible intrados. It ishowever frequent that the teeth do not follow exactly the curvature ofthe trays 1 and 2 and that one tooth finds itself corresponding to theextrados 3 when the impression is taken. In this situation, the splintcannot at all adapt to the arch.

FIG. 4 represents a tray of a device having an articulated frameaccording to the invention. In this device, the extrados includes atleast one flexible joint so as to make an articulated frame to followthe patient's dental conformation, even in the case where the teeth areimplanted irregularly.

In this simple embodiment, the inventive device is limited to a singlecentral flexion point, situated corresponding to the midsagittal plane.The flexible joint is obtained by providing a slit 13 in the extrados 3.The considerably higher flexibility corresponding to the slit 13 allowsthe extrados 3 to be articulated. A flexible metallic or plastic element14 can be inserted to connect the two right and left halves of theextrados 3. The inventive system can include one or several slitsaccording to the sought degree of adaptability.

FIG. 5 represents, for the sake of simplification, the upper tray 1only. The features that are characteristic of this embodiment of theinvention can obviously also be advantageously incorporated into thelower tray 2.

The central slit 13 also allows the two trays to align correctly whenthe impression is taken. Optionally, the same function can be ensured bymarks, preferably convex, engraved to this effect on both trays.

In the frame of the present invention, the elastic loops could bereplaced by other equivalent means, for example by springs, pistons,flexible tongues provided in one or the other tray or by magnets.

Advantageously, the frame comprises a plurality of flexible joints toadapt to a wider range of dental conformations. FIG. 5 represents a trayof a device according to the invention provided with an extrados formingan articulated frame. The extrados 3 includes in this case threeflexible joints 12 made by thinning the outer walls. Preferably, theextrados 3 will be made of a polymer capable of being formed by molding,having a good elasticity and being capable of bearing a great number offlexion cycles, for example of a thermoplastic elastomer.

The materials of which the extrados and the intrados are made areselected so as to provide a good adhesion between these two parts. Agood chemical compatibility is thus important in order to achieve thisresult. The adhesion of the extrados with the intrados can be furtherimproved by providing ribs or cavities in the extrados to provide ahooking surface during molding.

FIGS. 13, 14 and 15 show the flexible extrados of the lower tray 8 of asplint according to another embodiment of the invention.

In this embodiment, the flexible joints are made by thinning the innerwalls of the extrados, which has the advantage of maintaining an outersurface that is perfectly smooth and of avoiding concave outer surfacesthat are difficult to clean. The extrados includes in this variantembodiment alternating thin sections 23 and more rigid ribs 22. The thinsections 23 work essentially in flexion and in extension and allow theextrados to follow the general shape of the dental arch. The ribs 22, onthe other hand, provide sufficient rigidity to ensure the splint'slateral stability against the teeth and notably against the lingual andlabial sides of the teeth.

It is important for the stability of the splint and for the dentalhealth that the flanks 3 l and 3 b of the extrados exert, through theirrigidity, two opposed lateral forces on the lingual and labial sides ofthe teeth respectively. The inventive device, through itsconformability, allows the symmetrical positioning of the two flanks 3 land 3 b relative to the teeth and consequently an efficient holdingwithout asymmetric efforts, even if the teeth are positionedirregularly.

The conformability of the inventive trays allows the traction exerted bythe elastic loops 6 to be spread correctly on a large number of teeth,typically 20 or more. It is thus possible in this manner to avoidcollateral damages that could arise if the advancement force were to beapplied on a limited number of teeth (for example deformation of theocclusion plane or displacement of teeth).

Advantageously, the zones more solicited in extension and in compressionhave thin curved walls 24, 25 to ensure greater elongations andcompressions thanks to their flexibility. The curvature of the walls 24and 25 could be towards the inside (concave) or towards the outside(convex) depending on the need.

FIG. 18 represents diagrammatically a cross section of the extrados 3along the plane AA of FIG. 13. One can see the thin section 23,traversed by the cross section plane AA, and the rib 22 in thebackground.

Another embodiment of the invention will now be described with referenceto FIG. 6. In this embodiment, a flexible and articulated frame isinserted inside a tray 4 of a flexible and thermoformable material. Theflexible frame is composed of a succession of rigid U-shaped elements 9,open towards the dental arch, connected by thinner flexible elements 10and 10 a. Advantageously, the articulated frame is made of a singlepiece by molding a suitable material having a good elasticity anddeformability and capable of bearing a very high number of flexioncycles at its thin section.

The flexible articulations 10 and 10 a allow the frame to deform in thethree dimensions of space, horizontally and vertically, as well astorsion movements. In this manner, the inventive device can fitperfectly the dental conformation in three dimensions, for example toadapt to the natural curvature of the dental occlusion surface or to anon parallel implantation of the teeth. (The designations “horizontal”and “vertical” refer here to the conventional orientation of the splintwhen it is worn by a wearer in upright position).

The mandibular advancement splint according to this embodiment of theinvention has an outer surface that is completely flexible and thusprovides superior comfort as compared with devices having rigid orsemi-rigid outer surfaces. FIGS. 7 and 9 show two cross sections of thetray 4 of FIG. 6 in correspondence with the elements 9 and 10.

Another advantage of this embodiment of the invention is that the risksof the inner frame and the thermoformable part becoming unstuck arepractically nil. The thermoformable tray 4 is molded around the flexibleframe and completely envelops it.

FIG. 19 represents a top view of the lower element 2 of the inventiveadvancement splint made according to a preferred variant of theembodiment of the invention that has just been described. In thisvariant embodiment, the flexible articulated frame, visible intransparency in the figure, is composed of a greater number of U-shapedelements 91 relatively rigid, open towards the dental arch, connected bya relatively flexible ridge 10 or another flexible element that connectsthe elements 91. The articulated frame is made of a single piece bymolding an appropriate material having a good elasticity anddeformability, a minimal creep and capable of bearing a very high numberof flexion cycles at its thin section, such for example as polyacetal ofmedical quality. Advantageously, the hooks 7 provided for fastening theelastic loop, are made integrally in the frame.

Preferably, the relatively rigid elements 91 have openings 99 to allowthe thermoformable material to pass more easily when the tray 4 ismolded around the frame. This characteristic could also be adopted inthe other embodiments of the invention described, depending on the case.

FIG. 20 shows in three dimensions the lower inner frame of FIG. 19. Inthis variant embodiment, the frame bears two pairs of additional hooks 7a, 7 b instead of a single pair. This arrangement makes it possible tomodulate easily the advancement force exerted by the elastic bands (notrepresented) by simply selecting the fastening hook.

FIG. 21 shows, in three dimensions, the lower cradle 2, after thethermoformable tray 4 has been molded.

FIG. 22 represents, in the same way as FIG. 20, a frame for an uppercradle having a certain number of relatively rigid U-shaped elements 92open towards the dental arch, connected by flexible ridges. FIG. 23shows the upper cradle 1 after the thermoformable material 4 has beenmolded.

This embodiment of the invention has the advantage that the cradles candeform, when the impression is made, in all directions in space. Theinventive frame can thus not only open and close in the horizontal planeto adapt to a more or less open mandible or jaw, but it can also curvevertically to fit the curvature of the occlusion surface and twistaccording to the direction in which the teeth are implanted.

Thanks to this characteristic, the inventive advancement splint canadapt, in three dimensions, to any dental conformation of the wearer.

FIG. 9 illustrates an interface element 15 that intervenes when theimpression is taken for the inventive device. The aim of this device isto prevent, when the impression is made, the two flanks 3 l and 3 b frommoving apart, which would have the effect of reducing the pressure onthe lingual and labial sides of the teeth and, consequently, thestability of the splint. To this effect, the trays are inserted, formaking the impression only, in two interface elements in the shape ofdisposable flexible cradles 15 that prevent the surface 8 from deformingand the flanks 3 l and 3 b from moving apart.

It is also important that the two trays that make up the advancementsplint have two sliding planes 8 perfectly adapted to one another. Usinginterface elements 15 makes it possible to prevent any deformation ofsaid planes when the impression is made.

A symmetric cradle is provided for the lower tray. Once the cradles 1and 2 have been molded on the arches, the interface elements 15 can beremoved after the thermoformable elements 4 have cooled.

These interface elements 15 can also be advantageously used in otherembodiments presented, whilst remaining within the frame of the presentinvention.

Optionally, the sliding plane 8 of at least one of the trays 1 and 2 hasa plurality of parallel convex striations 81 or other types of relief toimprove sliding as represented in FIG. 3.

With reference to FIGS. 11 and 12, the lower tray 2 has, at the frontextremity, a protrusion 16 with an inclined plane 15, oriented in thedirection of increasing the advancement force during a backward movementof the mandible, thus contributing to keeping the advanced position. Ithas been seen that, during sleep, the mandible sometimes involuntarilymoves backwards. These movements are physiological during sleep anddeglutition and it would not be conceivable to lock the mandible in astatic advanced position. This embodiment thus makes it easier for themandible to return to the advanced position after these movements.

FIG. 10 represents a thermometer for measuring the temperature of a hotwater bath designed to facilitate the shaping of the inventive devices.

Making the impression includes previously immersing the trays in a coldwater bath that is then brought to a temperature of about 75° C.

Traditional glass thermometers have the tendency of moving to the bottomof the bath 100 and will thus record a much higher temperature than theprescribed temperature of the bath. Furthermore, devices that are toolight, for example those using liquid crystals, are easily transportedby the movements of simmering liquid and reading them is not easy.

The thermometer 20 has an asymmetric floater 21 that determines ahydrostatic equilibrium position inclined relatively to the verticalaxis of the thermometer 20. This arrangement makes it easier to read thetemperature. The thermometer's equilibrium position is preferably chosenso that the thermometer's sensing bulb is, in the water, at the sameheight as the floating trays 1 and 2.

With reference to FIGS. 16 and 17, another embodiment of the presentinvention provides a flexible elastic tongue 28 made integrally in thesupper tray 1 during molding. Other positions, for example further back,are however possible and comprised within the present invention.

The tongue 28 rests against the lower tray 2 when the advancement is inits normal use position and exerts a advancement force on the lower trayand the postero-anterior direction, thus positioning the mandible in thesought advanced position to prevent snoring, whilst allowing sufficientfreedom for involuntary movements during sleep.

1. Mandibular advancement splint, having a first tray for enveloping theupper dental arch and a second tray for enveloping the lower dental archof the mouth cavity, the splint including advancement means connectingsaid first and second trays, capable of exerting an advancement forceonto said second tray in the postero-anterior direction, characterizedin that at least one of said first and second trays includes anarticulated frame, allowing deformation along three dimensions, to adaptto the wearer's dental conformation, wherein said articulated frame ismade of a single injected piece having relatively rigid elements toexert a holding force against the labial and lingual sides of the teeth,and flexible elements to allow said frame to articulate and/or deform.2. The mandibular advancement splint of claim 1, having elements ofthermoformable plastic material in said first and second trays to adaptto the wearer's dental conformation.
 3. The mandibular advancementsplint of claim 1, wherein said advancement means include elastic loops.4. The mandibular advancement splint of claim 2 wherein said frame isinside said elements of thermoformable plastic material.
 5. Themandibular advancement splint of claim 1, wherein said frame includes aplurality of prehension elements open towards the dental arch andcapable of exerting a holding action on the dental and lingual sides ofthe teeth, said prehension elements being connected by flexiblearticulations.
 6. The mandibular advancement splint of claim 1, whereinsaid first tray and said second tray have visual indicia to make easierthe relative alignment of said first and second trays.